Microsoft Corp. launched a redesigned MSN portal optimized for mobile phones on Sunday, stepping up its offering at a time when more powerful devices increase the demand for richer content on handsets.

U.S. mobile Internet use still represents only a fraction of computer-based Web usage, but technology heavyweights like Microsoft see increasingly powerful mobile phones and faster networks opening the door for new services and content.

We firmly believe there is an inflection point here, said Phil Holden, Microsoft's director of mobile Web services. There's a new battle, a new frontline developing on the mobile phone.

Microsoft's new MSN Mobile portal -- -- offers news, sports information, entertainment features and access to services like e-mail, search, maps and instant messaging all on one page.

When a user accesses the portal, the MSN platform detects the handset and optimizes the site for that device, adjusting things like font sizes for different screens.

The number of U.S. mobile Internet users is expected to more than triple to 110 million in 2011 from the current 32 million, according to Sterling Market Intelligence and Opus Research.

Microsoft faces a lot of competition in the space.

Its Web competitors Google Inc. and Yahoo Inc. are trying to establish a mobile Internet presence while wireless carriers want to keep their consumers close with portals of their own.

The ultimate prize for all the players is to gain a foothold in the market for mobile advertising. ABI Research has forecast global mobile marketing and advertising to increase sixfold to $19 billion by 2011 from an estimated $3 billion by the end of 2007.

Microsoft said it will not place advertising on the portal right away, but said it expects to have either banner, text or click-to-call ads in place this year.

The launch of the new MSN Mobile portal comes a few weeks before Apple Inc. releases its (Nasdaq:AAPL - news) highly anticipated iPhone, which features a Safari browser that allows users to view full Web pages by zooming in and out.

Greg Sterling, founding principal of research firm Sterling Market Intelligence, said the iPhone and the new MSN portal reflect how companies are trying to address consumer dissatisfaction with surfing the Internet on mobile phones.

The majority of users are not surfing the mobile Internet yet, but there is pent-up demand for content on mobile phones, said Sterling, noting that small screens and slow networks contributed to a poor experience for most users.